It is becoming standard practice in many bolting situations to tighten bolts until they reach their yield point. There are many advantages in tightening bolts to their yield point. An article entitled "Fastener Tension Control-- What It's All About" in the November 1976 issue of Assembly Engineering gives an excellent summary of the advantages of such tightening and describes several state-of-the-art wrenching systems which are being used for such tightening; this article is herein incorporated by reference.
One problem encountered when a bolt is tightened to its yield point is that the bolt then has no built-in overload protection against further yielding or against loss of preload. I outlined the nature of this problem and gave a process for dealing with it in my co-pending application. "Process for Creating Overload Protection Against Yielding in Bolts," Ser. No. 693,546, which will become U.S. Pat. No. 4,037,282 on July 26, 1977, herein incorporated by reference.